Wiper plug having disintegrable flow passage obstructing portion and method of using same

ABSTRACT

A wiper plug including a body having one or more wiping elements radially extending therefrom. An obstructing portion is disintegrable upon exposure to a selected fluid in order to permit fluid communication across the wiper plug when the obstructing portion is disintegrated. A method of using a wiper plug is also included.

BACKGROUND

It is common in the downhole drilling and completions industry to cement a borehole after drilling and installing casing in the borehole. The cementation operation may include pumping a wiper plug downhole to assist in directing the cement through a port, e.g., of a shoe, located at a distal end of a casing string in order to fill an annulus between the casing string and the wall of the borehole with cement. The presence of the wiper plug within the casing sting after the cementation operation may hinder the ability to perform subsequent fluid circulation operations, e.g., which may be used for enabling tools to be pumped downhole. While systems such as drillable wiper plugs have been devised to enable the wiper plugs to be removed, and work sufficiently for their intended purpose, the industry would well receive alternative wiper plug systems.

SUMMARY

A wiper plug, including a body having one or more wiping elements radially extending therefrom; and an obstructing portion disintegrable upon exposure to a selected fluid in order to permit fluid communication across the wiper plug when the obstructing portion is disintegrated.

A method of using a wiper plug including engaging one or more wiping elements of the wiper plug within a string; moving the wiper plug through the string; impeding fluid flow across the wiper plug with an obstructing portion of the wiper plug; exposing the obstructing portion to a selected fluid; disintegrating the obstructing portion with the selected fluid; and communicating fluid across the wiper plug.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 is a schematic cross-sectional view of a system for performing a cementing operation in a borehole;

FIG. 2 is a cross-sectional view of a wiper plug according to one embodiment disclosed herein;

FIG. 3 is a cross-sectional view of a wiper plug according to another embodiment disclosed herein; and

FIG. 4 is a cross-sectional view of a wiper plug according to yet another embodiment disclosed herein.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring now to FIG. 1, a completion system 100 for performing a downhole cementing operation is schematically illustrated. Specifically, an annulus 102 located radially between a casing string 104 and a borehole 106 is intended to be cemented by use of the system 100. The casing string 104 includes a liner 108 that is hung from a relatively up-hole portion of the casing 104 and is also cemented. The casing string 104 includes a shoe 110 permitting communication of cement and other fluids between the casing string 104 and the annulus 102. The shoe 110 can be equipped with one or more floats or check valve devices, e.g., as a so-called float shoe, to permit fluid flow in primarily one direction, e.g., to prevent the cement or other fluids from entering the casing string 104 from the annulus 102. A float collar 112 can also be included having one or more floats or other check valve devices for a similar purpose. Cement can be supplied via a running string 114 that is insertable into the casing string 104.

In order to promote the progression of cement through the casing string 104 and into the annulus 102, a wiper plug 10 can be pumped through the running string 114. The wiper plug 10 may also be referred to as a pump down plug or wiper dart. Generally, a pressurized fluid can be supplied to the up-hole side of the wiper plug 10 to propel the plug 10 through the running string 114, thereby displacing the cement downhole of the plug 10 as the plug 10 progresses through the running string 114 and/or the liner 108. In this way, the plug 10 urges the cement out through the casing string 104, e.g., via a port or ports in the shoe 110, in order to fill the annulus 102 with the cement.

The wiper plug 10 includes one or more wiper elements 12 that sealingly engage the walls of the running string 114. The wiper plug 10 is arranged to prevent fluid communication across the plug 10, e.g., in both the up-hole and downhole directions. That is, the engagement of the wiper elements 12 within the running string 114 facilitates the ability of pressurized fluid to propel the plug 10 downhole as well as to urge cement and other fluids (e.g., spacer fluid separating the cement and the wiper plug 10) in the downhole direction while preventing the cement or other fluids from flowing back up-hole across the plug 10. The wiper elements may be formed from any suitable material, e.g., resilient and/or elastomeric material, take any shape, e.g., be in the form of wiper cups. The plug 10 also includes a flow bore or passage 14 formed therethrough. An obstructing portion 16 is initially present in the flow passage 14 in order to prevent fluid flow through the passage 14. In this way, the obstructing portion 16 enables pressurized fluid to propel the plug 10 through the running string 114 and prevents cement from flowing up-hole past the plug 10, as noted above.

A liner wiper 116 is included at the end of the running string 114. The plug 10 is configured to land in and sealingly engage the liner wiper 116. The liner wiper 116 includes wiping elements 118 configured to sealing engage against the liner 108 and operate similar to the wiping elements 12 of the plug 10, but with respect to the liner 108. Continued pressurization releases the liner wiper 116, together with the plug 10, to continue to urge cement and/or other fluids through the liner 108 and into the annulus 102 via the shoe 110. A landing collar 120 is arranged to receive the liner wiper 116 at the end of its movement through the liner 108.

After cementing, it may be desired to circulate and/or pump fluids through the casing string 104. In one embodiment, a perforation gun or other tool is carried or urged to a desired position within the casing string 104 in a pumped flow of fluid within the casing 104. As noted above, however, the wiper plug 10 is sealingly engaged with the liner wiper 116, and the liner wiper 116 sealing engaged with the liner 108, thereby blocking fluid flow through these components and hindering the ability to pump fluid through the casing string 104. To this end, the obstructing portion 16 of the plug 10 is disintegrable upon exposure to a selected fluid in order to remove the obstructing element 16 from the fluid passage 14 and thereby permit fluid to flow through the plug 10 via the passage 14. As used herein, “disintegrable” refers to a material or component that is consumable, corrodible, degradable, decomposable, dissolvable, or otherwise removable in response to the selected fluid. It is to be understood that use herein of the term “disintegrate,” or any of its forms (e.g., “disintegration”, etc.), incorporates the stated meaning. The selected fluid could be a fluid present or naturally occurring within the borehole 106, e.g., a downhole fluid such as brine, water, oil, etc., a fluid that is delivered or pumped downhole specifically for the purpose of disintegrating the obstructing portion 16, e.g., solvents, acids, etc., or combinations thereof

Three specific embodiments for the plug 10 are illustrated in FIGS. 2-4, labeled as plugs 10 a, 10 b, and 10 c, respectively. It is to be understood that any description generally with respect to the plug 10 applies generally to the plugs 10 a, 10 b, and 10 c and that the plugs 10 a, 10 b, and 10 c are provided as examples only and are not to be considered limiting. Additionally, it is to be understood that the plugs 10, 10 a, 10 b, and 10 c may include components that share a similar structure and purpose and are provided with the same reference numeral. As discussed in more detail below, the primary difference between the plugs 10 a, 10 b, and 10 c is the structure of the obstructing portion included in each embodiment, identified with the numerals 16 a, 16 b, and 16 c, respectively. As with the plug 10, and description of the obstructing portion 16 generally applies to each of the members 16 a, 16 b, and 16 c.

The plug 10 a is arranged generally as described above with respect to the plug 10, i.e., having a plurality of the wiping elements 12 radially extending from a body 18 and with the flow passage 14 formed therethrough. An obstructing portion 16 a is disposed within the flow passage 14 in order to impede the flow of fluid through the flow passage 14 when the obstructing portion 16 a is present (e.g., as with the obstructing portion 16 in general). The obstructing portions 16 is disposed in the flow passage 14 between the body 18 and a nose member 20 of the plug 10. The nose member 20 is couplable to the body 18, e.g., via a threaded connection, which enables the obstructing portion 16 a to be so positioned. Connection of the nose member 20 to the body 18 traps the obstructing portion 16 a in the flow passage 14. The obstructing portion 16 a includes a pair of seal elements 22 a to sealingly engage within the passage 14 to facilitate the blockage, impedance, or hindrance of fluid flow through the passage 14. The seal elements 22 a can be any desired sealing element, e.g., o-rings or other elastomeric sealing elements. The nose member 20 includes one or more ports 24 that enable fluid communication through the flow passage 14 when the obstructing member 16 a is disintegrated.

The plug 10 b resembles the plug 10 a in many respects, e.g., including the wiper elements 12, flow passage 14, body 18, nose 20, ports 24, etc. As noted above, the plug 10 b includes the corresponding obstructing portion 16 b, which differs from the portion 16 a discussed above (and the portion 16 c discussed below). Accordingly, only the section of the plug 10 b illustrating the portion 16 b is illustrated in FIG. 3. Specifically, the portion 16 b includes a flange 26 that becomes pinched, pressed, or gripped between the nose member 20 and the body 18 when coupled together, thereby firmly holding the portion 16 b in position in the flow passage 14. The portion 16 b includes a seal element 22 b that sealingly engages with the body 18 (e.g., as opposed to the seal elements 22 a engaging with the nose 20) in order to block, impede, or otherwise hinder fluid from flowing through the passage 14.

The plug 10 c is shown in FIG. 4 and generally resembles both the plugs 10 a and 10 b, discussed above, but includes the obstructing portion 16 c in lieu of the portions 16 a and 16 b, respectively. The portion 16 c shares the flange 26 of the portion 16 b, e.g., in order to enable the portion 16 c to be firmly held in position between the nose 20 and the body 18. Unlike the portion 16 b, the obstructing portion 16 c includes a seal element 22 c that sealingly engages with the nose 20 (similar to the sealing elements 22 a).

It is to of course be appreciated that the obstructing portion 16, regardless of particular form, can be sealingly engaged with any component of the plug 10, e.g., the body 18, the nose 20, or some other part. Additionally, any suitable sealing device or element or manner of sealing could be utilized. For example, in one embodiment, metal-to-metal seals are formed by wedging the obstructing portion 16 in place between the nose 20 and the body 18 and a separate sealing element (e.g., the elements 22 a, 22 b, and/or 22 c) are not included. Additionally, combinations including elements of the embodiments can be made. For example, in one embodiment the obstructing portion 16 resembles a combination of the portions 16 b and 16 c, including a flange, e.g., the flange 26 and sealing elements to seal the portion with both the body 18 and the nose 20, e.g., both the sealing elements 22 b and 22 c.

It is additionally to be appreciated that obstructing portions can take forms different than those illustrated. For example, in one embodiment the entirety of the nose member 20 is disintegrable and forms the disintegrable portion 16. In one embodiment, some or all of the body 18 is disintegrable to form the obstructing portion 16. In one embodiment the body 18 and the nose 20 are integrally formed, and the obstructing portion 16 is either integral or separately disposed therewith, e.g., held in place with dogs, ratchets, set screws, etc. In one embodiment, only a portion of the obstructing portion 16 is made of disintegrable material, e.g., only the component holding the obstructing portion 16 within the flow passage 14 such as the flange 26, or the aforementioned dogs, ratchets, set screws, etc. In one embodiment, the obstructing portion 16 is a cap, film, or layer that is secured on or about the body 18, e.g., at the end opposite to the nose 20, on the nose 20, about the ports 24, etc.

An example of materials that are suitable for use in manufacturing the obstructing portion 16 and/or other disintegrable portions of the plug 10 include those commercially available from Baker Hughes Incorporated under the trade name IN-TALLIC™. A description of suitable materials can also be found in United States Patent Publication No. 2011/0135953 (Xu et al.), which Patent Publication is hereby incorporated by reference in its entirety. These lightweight, high-strength and selectably and controllably degradable materials include fully-dense, sintered powder compacts formed from coated powder materials that include various lightweight particle cores and core materials having various single layer and multilayer nanoscale coatings. These powder compacts are made from coated metallic powders that include various electrochemically-active (e.g., having relatively higher standard oxidation potentials) lightweight, high-strength particle cores and core materials, such as electrochemically active metals, that are dispersed within a cellular nanomatrix formed from the various nanoscale metallic coating layers of metallic coating materials, and are particularly useful in borehole applications. Suitable core materials include electrochemically active metals having a standard oxidation potential greater than or equal to that of Zn, including as Mg, Al, Mn or Zn or alloys or combinations thereof For example, tertiary Mg—Al—X alloys may include, by weight, up to about 85% Mg, up to about 15% Al and up to about 5% X, where X is another material. The core material may also include a rare earth element such as Sc, Y, La, Ce, Pr, Nd or Er, or a combination of rare earth elements. In other embodiments, the materials could include other metals having a standard oxidation potential less than that of Zn. Also, suitable non-metallic materials include ceramics, glasses (e.g., hollow glass microspheres), carbon, or a combination thereof In one embodiment, the material has a substantially uniform average thickness between dispersed particles of about 50 nm to about 5000 nm. In one embodiment, the coating layers are formed from Al, Ni, W or Al₂O₃, or combinations thereof In one embodiment, the coating is a multi-layer coating, for example, comprising a first Al layer, an Al₂O₃ layer, and a second Al layer. In some embodiments, the coating may have a thickness of about 25 nm to about 2500 nm. These powder compacts provide a unique and advantageous combination of mechanical strength properties, such as compression and shear strength, low density and selectable and controllable corrosion properties, particularly rapid and controlled dissolution in various borehole fluids. The fluids may include any number of ionic fluids or highly polar fluids, such as those that contain various chlorides. Examples include fluids comprising potassium chloride (KCl), hydrochloric acid (HCl), calcium chloride (CaCl₂), calcium bromide (CaBr₂) or zinc bromide (ZnBr₂).

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. 

What is claimed is:
 1. A wiper plug, comprising: a body having one or more wiping elements radially extending therefrom; and an obstructing portion disintegrable upon exposure to a selected fluid in order to permit fluid communication across the wiper plug when the obstructing portion is disintegrated.
 2. The wiper plug of claim 1, wherein the body includes a flow passage formed therein and the obstructing portion is initially disposed to block flow through the flow passage.
 3. The wiper plug of claim 2, further comprising one or more seal elements sealingly engaging the obstructing portion within the flow passage.
 4. The wiper plug of claim 2, further comprising a nose member couplable to the body, the flow passage formed also through the nose member, and wherein the obstructing portion is located between the nose member and the body.
 5. The wiper plug of claim 4, wherein the obstructing portion includes a flange that is trapped between the nose member and body to hold the obstructing portion in the flow passage.
 6. The wiper plug of claim 4, further comprising one or more seal elements sealingly engaging the obstructing portion within the flow passage.
 7. The wiper plug of claim 6, wherein the one or more seal elements sealingly engage the obstructing portion with the body, the nose, or a combination including at least one of the foregoing.
 8. A completion system including the wiper plug of claim
 1. 9. The system of claim 8, further comprising a casing string disposed in a borehole and a running string disposed in the casing string, the wiper plug configured to travel through the running string to urge cement through the running string and out through the casing string into an annulus between the casing string and the borehole.
 10. The system of claim 9, further comprising a liner wiper configured to sealingly receive the wiper plug and to together travel through a liner of the casing string to urge the cement into the annulus.
 11. The system of claim 9, wherein the casing string includes at least one float for enabling cement or other fluids to flow from the casing string into the annulus while preventing the flow of cement or other fluids into the casing string from the annulus.
 12. A method of using a wiper plug comprising: engaging one or more wiping elements of the wiper plug within a string; moving the wiper plug through the string; impeding fluid flow across the wiper plug with an obstructing portion of the wiper plug; exposing the obstructing portion to a selected fluid; disintegrating the obstructing portion with the selected fluid; and communicating fluid across the wiper plug.
 13. The method of claim 12, wherein the obstructing portion is disposed in a flow passage formed through a body of the wiper plug.
 14. The method of claim 12, wherein the string is a running string disposed in a casing string installed in a borehole.
 15. The method of claim 14, wherein moving the wiper plug includes urging cement out of the running string and the casing string into an annulus formed between the borehole and the casing string.
 16. The method of claim 14, further comprising landing the wiper plug in a liner wiper and moving the liner wiper together with the wiper plug through a liner of the casing string before communicating fluid across the wiper plug. 